The present invention relates to a power take-off apparatus in an automotive vehicle such as a dump truck, a cement mixer truck, a fire truck or the like, and more particularly to a power take-off apparatus in an automotive vehicle equipped with an automatic power transmission including a rotary element arranged to be driven by a prime mover of the vehicle when the power transmission is conditioned in a neutral position during stopping of the vehicle and to be arrested when the power transmission is conditioned in a forward position.
Such a conventional power take-off apparatus as described above comprises a drive gear mounted on the rotary element in the form of a clutch drum for rotation therewith, a driven gear arranged to be brought into meshing engagement with the drive gear during stopping of the vehicle, and an electrically operated shift mechanism including an electric motor and a linkage connected to the electric motor to move the driven gear toward and away from the drive gear in response to energization of the electric motor. In operation of the conventional power take-off apparatus, when the electric motor of the shift mechanism is energized in a condition where the power transmission is maintained in the forward position during stopping of the vehicle, the driven gear is brought into meshing engagement with the arrested drive gear. Thus, the output power of the prime mover is taken out through the gears when the power transmission is shifted to the neutral position. In such operation of the shift mechanism, it has been experienced that if the driven gear is not meshed with the drive gear, the electric motor must be energized to move the driven gear away from the drive gear, and also the power transmission must be shifted to the neutral position to rotate the drive gear. Thereafter, the power transmission is returned to the forward position, and subsequently the electric motor is energized to establish meshing engagement of the driven gear with the drive gear. It has been also experienced that if the electric motor is energized by an error in a condition where the power transmission is conditioned in the neutral position during stopping of the vehicle, the driven gear is moved toward the drive gear being driven by the output power of the prime mover. This causes undesired noises in meshing engagement of the gears.